DIY Coke Can Solar Heating Panel

From Coke Cans to Solar Heating Panel

Upcycling is a way of life here, but that is only one reason I love our new Coke Can Solar Heating Panel. The best part is all that lovely heat in our old house. Before we installed the panel, we often saw winter temperatures warmer OUTSIDE than inside. Admittedly, the winters in Northland aren’t known for being punishing, but going outside to get warmer isn’t something I like to do.

Plus, Frugal Man calculates that using the system will cost us approximately $1.50 in electricity per year. No typo there. That is PER YEAR. You can see why I gaze upon our panel fondly.

DIY Coke Can Solar Heating Panel, installed on the house.

The panel consists of Coke and beer cans, plywood and a sheet of polycarbonate. We used a whole sheet of plywood as a base, so it is HUGE 2.4m x 1.2m (7’11” x 4′). Many people build similar heaters with old window panes, so don’t think they all have to be so massive. It’s just that we weren’t messing about when we built ours. We mean business!

How we built the solar heating panel

We started out with a whole heap of cans. Over 300 of them.

Cans for the solar heating panel

Some we collected on our own over the summer, but the vast majority were donated by friends or scrounged. Frugal Man cut out the bottoms of the cans with a drill press then I washed them. There were many slugs. And snails. And the house smelled like stale beer.

Next Frugal Man cut the tops of the cans to form baffles. I tried to do this, but the tin snips were too big for my hands and we couldn’t find a smaller version that I could use comfortably. He worked on baffling these over the course of several evenings whilst watching TV.

Can top, cut to produce baffles.

When he was done baffling the tops, he glued the cans together in sets of three. They were eventually glued together in columns of 16, but sets of three were much more manageable to have sitting around the living room.

Once the cans were glued in threes, he spray painted them a matte black all the way around. I thought he’d just paint the front where the sun would hit, but he’d read that you got improved performance with an all around spray. We used about seven cans of spray paint.

He installed the cans in columns in the plywood box he built that we’d painted with some dark brown fence paint we had lying around. We ended up with 17 rows of 16 can high columns for a total of 272 cans. The columns fit into holes he’d drilled in the plywood that connect the cans to the top and bottom manifolds.

Solar panel frame, before painting and can installation

He then screwed a large sheet of polycarbonate on to cover the can area.

How the solar heating panel works

The air from the house enters into a round opening in the back of the bottom manifold. Once in the black cans, the air heats up and naturally rises to the top manifold. The air then re-enters the house through the round opening in the back of the top manifold.

Some people leave it at that and have a completely passive system. Frugal Man decided on a more active approach for us. On the inside of the house, he installed two small, 12V, 100,000 hour life at 40C (104F), super-quiet, low-power fans from Jaycar. One pushes air into the panel at the bottom and the other pulls heated air out of the top. He’s put the fans on a temperature controller-the same type we use for our ultra-efficient Chest Fridge– so they start running around 29C(84F). We still get warm air trickling in at lower temperatures as you would with a passive system, but it isn’t fan assisted.

He also cut a small sheet of clear plastic out of a Ziploc bag and installed it over the top inlet grill. The sheet is easily blown open when heat is entering the house, but it prevents cold air from streaming into the house by blocking the “waterfall effect”.

House modifications

Our system requires two holes in the side of the house through to our living room. Best to get THAT right the first time. No pressure.

Frugal Man, of course, managed perfectly, attracting the attention of smaller denizens of the house in the process. The calendulas got trampled in the process, but I can plant more.

Ed the nosy rosey Devon Rex investigates the lower hole in the house.

The system on the inside of the house looks nice and tidy. We have the two manifold holes, covered by grids and the temperature controller box next to the upper manifold inlet.

Our solar panel setup as seen from inside the house. Two inlets with grills and the temperature controller mounted by the top inlet.

Effect on temperatures in the house

The heat from our panel, spread across our great room, doesn’t immediately feel like a huge boost when it comes on. What DOES happen, is that the thermal mass of the whole large space is lifted by several degrees. Morning temperatures in our house this time of year, in the dead of winter, commonly range from 8C (46F) to 13C (55F). Without the solar heating panel, those numbers don’t increase much during the course of the day, as we have no sun from the north to heat the house with our house situation.

Using the panel, we are seeing temps rise into the 15C (59F) to 17C (63F) range. Not screamingly hot, by any means, but much more comfortable. In addition to the daytime lift in temperatures, we find the heat is holding in the house through to evening. It is much cheaper to heat the house to 20C (68F) from 17C(63F) than it is to do it from 13C (55F), assuming our heat pump could manage to get to that temperature before, which it couldn’t. A similar size heater warming a smaller room would, of course, produce warmer temperatures.

As the weather warms up when we head into spring, we should experience even more comfortable conditions with higher starting temperatures and longer sunshine hours giving the system a boost. As we head into summer, we will be able to block off the manifold inlets if we are getting too warm AND we have plans to turn the panel into a solar dehydrator for those sunny warm months. Two for one!

Cost and time to build the solar heating panel

With all of the materials: polycarbonate sheet (NZ$150), 1.5 sheets of plywood ($52), 7 cans of spay paint ($77), 2 tubes of silicon glue ($40), metal inlets, grills, fans, temperature controller, etc, the whole project priced out around $500. This puts it out of the “fun project” budget range and into “investment” range. So far we are happy with the performance and it should provide essentially free heat to us for a number of years, so it is an investment we are pleased to have made. Frugal Man worked on this project over several weekends, as well as the time he spent in the evenings cutting baffles, so expect to put some time in, if you decide to build your own.

If you are interested in the details of building your own Coke Can Solar Heating Panel, check out the many free plans available on Build It Solar. The site is an excellent repository for DIY solar projects of all kinds.

Very Impressive. Not everyone can make this kind of DIY things. But if you can’t make something like this, there are many solar products available in affordable rates, people should start using them and contribute something to save the environment.Aveen recently posted..Renogy 100W Mono Starter Kit Review

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Isabel
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September 10, 2014

Our only source of heat in the east side of New Mexico mountains is a wood burning stove. After 4 boys in the house I was never short of somebody hauling, splitting and stacking wood for the house. Now I am down to 1 son which is his last year in school and off he goes. I will find myself alone with my 3 yr old daughter. I have experience of hauling and splitting wood myself, but lets be honest it sucks when you come home late and its freezing, you have to wait till the heat from the stove warms the house till you can be comfortable. I love the source of heat and will continue to use my wood stove, but I love this idea to regulate the heat without having to worry about busted pipes if I leave home for more than a day. I am researching several ideas and plans to put more than one unit in my home. Thank you for the pictures and simple instructions I love it!!

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Fair comment. A window of equivalent size should give the same kind of energy into the house, providing that energy was absorbed rather than reflected (i.e. open the curtains and let the sun shine on the floor). The reasons we didn’t do that were cost and architecture. To put in a big double glazed window isn’t cheap, even if we did the cheap plastic double glazing. And the wall in question is one where we don’t particularly want a window because of the way the room works. If we take architectural measures to increase the performance of the house there are other options we’d do first, like enclosing the verandah and using that as a solar collector/sun room.

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This is absolutely incredible. I can’t believe that just a couple of soda cans can be made into a solar panel. And at $1.50 a year! I could be saving so much money during the very long winters of Utah!

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[…] and converting this energy into solar heat. What you see mounted on the side of this house is a soda can solar heating panel. This particular setup is able to warm the house it is mounted on. The total energy cost is $1.50 […]

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Due to PVC tubes not having the metallic property that actually as a reflective surface which bounces the sun light and heat around, No i don’t think (i Know) you can produce this type of heat generation from PVC tubes. Glass tubes with a reflective back ground may do the same job but you need a good way to distribute the heat.
I am working on my own design I will let you know if i succeed.Terry recently posted..Biofuels an Alternative Energy Source

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Frugal Man
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June 4, 2013

The cans are length ways, glued into columns that work like pipes so the air flows through the bottom one first then into the one above it and so on. Keeping excess heat out hasn’t been a problem for us, this house seldom overheats. But with the temps involved you should be able to just shutter off the air flow, particularly if the heater is vertically oriented. I’ve heard of problems with high efficiency solar heaters unable to get rid of heat when ‘turned off’, but those were roof-mounted ones angled to midday sun. My inclination is to just turn the fan off when not needed. If you’re somewhere hot I’d recommend sticking a thermometer in and seeing how hot it gets, then put a shutter or tarpaulin over it if it’s getting too hot or unpleasant.

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Seems like a really novel idea. I never thought that a solar heating panel could be made out of coke cans. Most importantly, the whole thing cost only $500, whereas an actual solar heating panel bought from the market would have run into a few thousand dollars. Kudos guys!

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z
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May 12, 2013

hey there good to see another kiwi with one.I made a 3mx1m panel 240 cans (40 rows of 6),i used a snap disk thermostat on at 50deg off at 45deg,and two fans as well,i insulated mine with polystyrene.Put out a max of 61 deg,thats the actual temp coming out of the blown air.We are in southland so it is very welcome when the sun is out,on ya mate

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Jimmy
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April 27, 2013

Anyone ever tried one of these on a roof? Might need to use slightly more power to move the air about but have the added benefit of more direct sunlight hours… Just wondering because I think I might put one on my roof.

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Frugal Man
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June 4, 2013

There are those that put them on the roof although they can overheat if there is no forced air circulation (natural convection wouldn’t work up there if the hot air has to be forced downwards). Ours is aimed at the morning sun because that’s when we most need it.

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Frugal Man
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April 26, 2013

Fair comment. A window of equivalent size should give the same kind of energy into the house, providing that energy was absorbed rather than reflected (i.e. open the curtains and let the sun shine on the floor). The reasons we didn’t do that were cost and architecture. To put in a big double glazed window isn’t cheap, even if we did the cheap plastic double glazing. And the wall in question is one where we don’t particularly want a window because of the way the room works. If we take architectural measures to increase the performance of the house there are other options we’d do first, like enclosing the verandah and using that as a solar collector/sun room.

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[…] returned for deposit yet? Well you might want to hang on to them. I found this excellent article over at the frugal kiwi blog that shows you how to make a solar heating panel from your coke cans. […]

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[…] it will pay for itself. The other option is self building like Frugal Kiwi did (see the post here DIY Coke Can Solar Heating Panel) or like the instructions given by Solar Cities. Obviously you need to be confident and get it […]

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Amazing. Our only “alternative” heating system is that we don’t use the AC but instead open all the windows at night to let the cold air in (we live at altitude). Before the temperatures soar during the day we close up the house again and it tends to stay cool. Pretty old fashioned but it works!

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Ginny
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July 25, 2012

We have plans to build one of these for our windows this winter. We rent, so there is no option of having this attached to the house (plus it would be on the front of the house, and a bit unsightly), so we plan to build boxes that fit into the windows. I have studied some plans, and with this option we won’t need to put a “front pane” on it since the heat unit will be up against the glass of the window. I have also heard it recommended to use “barbeque spray paint” which is designed to tolerate a higher temperature than standard spray paint. Since ours will also be smaller, we plan to use a little computer fan and a mini solar activated panel to run the fan. I will probably attach a small piece of dryer vent to it so that we can actually close the thermal curtains, and clip the curtains around the vent, so it will pump air into the room, but not be competing against the thermal exchange of our poorly sealed windows. I am so excited about this! The only downer is that we don’t drink soda or canned beer, so we don’t have an easy supply of cans… Its considered rather strange when we explain what we are doing to people when we ask them for their cans… I’m hoping to get at least one built this year, hopefully more, we’ll see how many cans we can come up with!

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Frugal Man
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July 25, 2012

Hi Ginny, there are two sides to heating a house – getting the heat in and stopping it leaking out. Provided your curtains aren’t reflective you’re getting the energy that you can in through the window anyway and having a can system inside may not do you as much extra good as you’d hope (you could just have the sunlight fall on a black surface that warms and radiates into the room for example, which is what I intend to try should my long held plan of walling in some verandah comes to pass). The other side is heat leaking out and that is where having some kind of double glazing can REALLY help. Even if it is just cling film separated from the glass a few millimeters or bubble wrap on the inside of windows you don’t care about seeing out of. People in NZ generally have insulation in ceilings and walls but then acres of cold single glazing.

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Frugal Man
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July 25, 2012

I should add that I don’t mean to put you off experimenting with these concepts! The idea is to be able to prototype quickly, see if it gives you what you want and revise to get a better result before building a ‘durable’ model. The fans we are using are 120mm computer fans that only use about 3w – they give reasonable volume air flow at very low noise. Hope you have fun with this project.

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Sounds like a lot of work, but a great pay-off. Re alt heat, I would love to get our wood stove hooked up this winter. It’s been sitting in our entryway for years, and with gas prices sky high, I really, really want an alternative before we head into this winter.

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Frugal Man
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July 24, 2012

@KrisBordessa The baffling is a combination of opening a big hole in the top of the can easily, and mixing up the air flow a bit to slow it down a little. It also acts as a heat sink for the can to help it radiate heat it into the air.

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Frugal Man
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July 24, 2012

Some technical stuff for those that need to know…
The fans (http://jaycar.co.nz/productView.asp?ID=YX2584) produce an alleged 68ft3/min of air flow (1.8 cubic metres/min) using about 3W each to do so, and the outlet air is heated to 45-55C in direct sun. So a rise from ambient inlet temp of 30-40C. I understand this performance is similar to a 1kw heater running. We have the panel facing north east so catch the early sun, losing it by about 1pm in winter. Orienting it more northerly and tilting a little would improve performance.

Given the large room volume it doesn’t produce a large increase in room temperature, but does seem to lift the temp a few degrees which then given the thermal mass of the house makes everything warmer after the sun has gone. The major problem with this house is that with few northerly windows it would cool down then stay cold, even as the surrounding air warmed. And increasing insulation a bit can actually make that worse.

The top vent has a thin sheet of plastic over the outlet that blows out of the way with hot air flow (even without the fans running) but sucks back over the vent at night when the panel would act like a big radiator and reverse the heat cycle (you can feel a moderate draft out of the bottom vent on a cold night if you open the top vent). It’s quite significant and happens on single glazed windows too but you don’t notice it there as a draught because it’s too diffuse (a good argument for double glazing!).

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I think this is absolutely amazing! Boy was your house chilly without it. Our place has never got down to less than 13 and that was only a couple of times. It looks totally brilliant as well. It’s a fab idea for baches. I love it!